The principal settlements have been made in the lower valley of the Surinam, or between that river and the Saramacca on the W. and the Commewyne on the E. The Surinam is the chief of a number of large rivers which rise in the Tumuc Humac range or the low hills between it and the sea, which they enter on the Dutch seaboard, between the Corentyn and the Maroni (Dutch _Corantijn_ and _Marowijne_), which form the boundaries with British and French territories respectively. Between the rivers of Dutch Guiana there are remarkable cross channels available during the floods at least. As the Maroni communicates with the Cottica, which is in turn a tributary of the Commewyne, a boat can pass from the Maroni to Paramaribo; thence by the Sommelsdijk canal it can reach the Saramacca; and from the Saramacca it can proceed up the Coppename, and by means of the Nickerie find its way to the Corentyn. The rivers are not navigable inland to any considerable extent, as their courses are interrupted by rapids. The interior of the country consists for the most part of low hills, though an extreme height of 3800 ft. is known in the Wilhelmina Kette, in the west of the colony, about 3 deg. 50' to 4 deg. N. The hinterland south of this latitude, and that part of the Tumuc Humac range along which the Dutch frontier runs, are, however, practically unexplored. Like the other territories of Guiana the Dutch colony is divided physically into a low coast-land, savannahs and almost impenetrable forest. Meteorological observations have been carried on at five stations (Paramaribo, Coronie, Sommelsdijk, Nieuw-Nickerie and Groningen). The mean range of temperature for the day, month and year shows little variation, being respectively 77.54 deg.-88.38 deg. F., 76.1 deg.-78.62 deg. F. and 70.52 deg.-90.14 deg. F. The north-east trade winds prevail throughout the year, but the rainfall varies considerably; for December and January the mean is respectively 8.58 and 9.57 in., for May and June 11.26 and 10.31 in., but for February and March 7.2 and 6.81 in., and for September 2.48 and 2.0 in. The seasons comprise a long and a short dry season, and a period of heavy and of slight rainfall.